There's garden gold in them thar leaves

Monday

Nov 30, 2009 at 3:13 PM

LEE REICH

Sometimes the nose can put the heart at odds with the head. Burning leaves was a common practice years ago, and that smell can bring up sweet, childhood memories of watching leafy mounds that had served as forts and hiding places disappear into flames and fragrant smoke.

But burning is no longer an acceptable way to deal with leaf piles. Once your brain gets the upper hand, you start thinking about air pollution, the ozone layer, smog and out-of-control fires.

There are much better things you can do with your leaves than burn them, even if you're not an avid gardener.

Just running over them with a lawnmower a few times might shred them enough so that they filter down into the lawn, to the lawn's benefit.

If leaves are so abundant that they would smother the lawn, go ahead and rake them — beneath your shrubs. A blanket of leaves there keeps the soil from washing away and exposing delicate feeder roots. That blanket of leaves also keeps the soil warmer in winter and cooler in summer. The result: Your shrubs will grow and look better.

For avid gardeners, leaves are an asset of which you can never have too much. As far as nutrients, leaves are not much different in composition from much-touted horse manure. And as leaves decompose, they become increasingly able to sponge up water — something to think about in August as you haul out the hose to drench your roses for the umpteenth time.

The fluffiness of leaves, as they decompose, also helps aerate the soil — something roots always appreciate.

The easiest way to go about tapping the benefits of autumn's bounty is as described above: Just rake them beneath shrubbery. If you're short on leaves, rake them beneath rhododendrons, mountain laurels, blueberries and azaleas first, because these shrubs appreciate them the most.

After shrubs, next in line for leaves are perennial flowers. Benefits in the perennial flower bed will be similar to those for shrubbery; in addition, the leafy mulch will prevent alternately freezing and thawing soil from heaving small or poorly rooted plants out of the ground in coming months.

Blanket the flower bed with a few inches of leaves, which will settle to perhaps an inch by spring. By this time next year, that layer will be almost gone and your soil will be ready for another dose. Tuck leaves right up around, but not on top of, poppy, delphinium, iris, coral bells and the few other perennials that do not like their crowns covered.

Vegetable gardens and annual flower beds also benefit from leaves. An advantage of leaves over some other mulches is that leaves are free of weed seeds. A disadvantage of blanketing an annual flower bed or vegetable garden with leaves — with any organic mulch, in fact — is that these mulches insulate the ground, delaying its warming in spring. Sidestep this disadvantage by temporarily raking off the mulch in spring, digging the leaves into the soil rather than using them as a mulch, or just delaying planting.

Yet another way to use leaves, anywhere in the garden, is to compost them first. A six-foot cylinder of chicken wire or snow fencing can hold as many leaves as about 25 large, plastic trash bags, and that's before the leaves even begin to settle and decompose.

No reason to rush it, but if you did want to hurry the decomposition, sprinkle some high nitrogen fertilizer, such as soybean meal, onto the leaves as you pile them up, and make sure the pile is moist throughout. Or you could shred the leaves. Or add leaves to your regular compost pile, where their high carbon content is a perfect complement to high nitrogen kitchen scraps.

Okay, if you are thoroughly inundated with leaves, there is one more option for dealing with them, besides burning. That option is to bag them up. Don't be surprised though if some leaf-hungry gardener snatches up nature's valuable bounty before they are picked up as "trash."